Digital TV receiving smart antenna control system and controlling method of the same

ABSTRACT

Disclosed is a digital TV smart antenna system and controlling method of the same, the system converges a smart antenna into an optimal reception by detecting a maximum signal power in a signal acquisition process for a fast acquisition performance and selectively assembling information such as signal power, multi-channel, SNR, and SER, and particularly, calculates signal power according to the antenna direction by fixing AGC as a specific value for detecting the maximum signal power.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.10/804,406, filed Mar. 18, 2004, now U.S. Pat. No. 7,242,424, whichpursuant to 35 U.S.C. § 119(a), claims the benefit of earlier filingdate and right of priority to Korean Application No. P2003-17197, filedon Mar. 19, 2003, the contents of which are hereby incorporated byreference as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a digital TV, and more particularly, toa digital TV receiving smart antenna control system and a controllingmethod of the same.

2. Discussion of the Related Art

Research about an antenna of a VSB (Vestigial Side Band) receiver isinsufficient yet because it is an early stage, the antenna of the VSBreceiver selected as a standard transmitting method of terrestrialbroadcasting channel of a digital TV.

However, in recent years, a concept and an idea about the antenna areactively proposed. It is known that an ATSC (Advanced Television SystemsCommittee) completed a standardization (CEA/EIA909) of the antenna.

An ATI (Next Wave) company experimentally applied the antenna to a realdigital TV and currently a field test is ongoing. In other words, a TVmarket is at a beginning stage and technology of the digital TVreceiving antenna is also at the early stage.

There is technology of antenna applied to a radio telecommunicationsystem (For example, a cellular phone, military wireless communication)in a related art. However, the technology is very complex and expensive.Therefore, more technical efforts are needed for applying the technologyto the digital TV.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a digital TV receivingsmart antenna control system and a controlling method of the same thatsubstantially obviates one or more problems due to limitations anddisadvantages of the related art.

An object of the present invention is to provide a digital TV receivingsmart antenna control system and a controlling method of the same forimproving a receiving performance of a receiver in a terrestrial channelin poor and kaleidoscope surroundings by applying a smart antenna and anantenna control system to a digital TV receiver

Another object of the present invention is to provide a digital TVreceiving smart antenna control system and a controlling method of thesame for improving quality of a receiving signal by removingmulti-channel at an indoor reception and improving the quality of thesignal through applying the smart antenna to a digital TV, and forproviding an excellent performance to transmitting towers at differentlocations.

Another object of the present invention is to provide a digital TVreceiving smart antenna control system and a controlling method of thesame for detecting a maximum signal power direction at a high speed bydetecting signal power at the high speed when a gain of the receiver inantenna control information is fixed at a predetermined level for anindoor reception, and by performing a 360° antenna scan by using thesignal power.

A further object of the present invention is to provide a digital TVreceiving smart antenna control system and a controlling method of thesame for providing an optimal receiving signal to a digital TV receiverby converging an optimal antenna direction by using an antenna directiontracing loop.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, adigital TV receiving smart antenna control system includes a smartantenna system for forming an antenna pattern suitable for signalreception by receiving mechanical or electrical antenna control signaland controlling a beam width, gain, and frequency characteristic, a VSBdemodulator for generating channel data for demodulating a VSB(Vestigial Side Band) signal received through the smart antenna system,generating channel data for the antenna pattern, and outputting thedemodulated VSB signal in a transport packet form, and an antennacontroller for receiving the channel data and auto gain controlinformation from the VSB demodulator and controlling the smart antennasystem by using the auto gain control information and the channelinformation set as a specific value.

In another aspect of the present invention, a digital TV receiving smartantenna control system includes the smart antenna system for forming anantenna pattern suitable for signal reception by receiving mechanical orelectrical antenna control signal and controlling a beam width, gain,and frequency characteristic, a tuner for tuning only a specific RFsignal in RF (Radio Frequency) signal received through a smart antennasystem, and converting the signal into an IF signal after automaticallycontrolling RF gain tuned according to RF gain control signal, a VSB(Vestigial Side Band) demodulator for demodulating after controlling theIF (Intermediate Frequency) signal gain according to IF gain controlsignal, a channel information detector for detecting channel informationsuch as signal power, multi-channel signal power, SNR (signal-to-noiseratio), and SER (Segment Error Rate) outputted from the VSB demodulator,determining the channel condition and outputting the channel informationand the channel conditions, and an antenna direction acquisitioncontroller for receiving signal power condition, multi-channel signalpower condition, SNR condition, SER condition, and signal powerinformation form the channel information detector and detecting andoutputting an antenna direction of the maximum signal power, fixing theRF gain control signal and IF gain control signal in acquisitionprocess, and changing the signals according to the receiving signal in atracking process.

Meanwhile, a controlling method of a digital TV receiving smart antennacontrol system includes the steps of acquiring maximum signal poweraccording to the antenna direction by using signal power information,multi-channel information, SNR information, and SER informationextracted from an input signal, and converging the smart antenna into anoptimal reception by selectively assembling the signal powerinformation, the multi-channel information, the SNR information, and theSER information.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings;

FIG. 1 illustrates a diagram showing a basic algorithm of a digital TVreceiving smart antenna control system in accordance with the presentinvention.

FIG. 2 illustrates a block diagram showing a digital TV receiving smartantenna control system in accordance with the present invention.

FIG. 3 illustrates a block diagram showing a first embodiment of an autogain controller of a VSB demodulator of FIG. 2.

FIG. 4 illustrates a block diagram showing a second embodiment of anauto gain controller of a VSB demodulator of FIG. 2.

FIG. 5 illustrates a detailed block diagram showing a channelinformation detector of FIG. 2.

FIG. 6 illustrates a detailed block diagram showing a first embodimentof a signal power information calculator of FIG. 3.

FIG. 7 illustrates a detailed block diagram showing a second embodimentof a signal power information calculator of FIG. 3.

FIG. 8 illustrates a detailed block diagram showing a first embodimentof a multi-channel signal power calculator of FIG. 3.

FIG. 9 illustrates a block diagram showing SNR information calculator ofFIG. 3.

FIG. 10 illustrates a diagram showing an example of input/output signalsof an antenna direction acquisition controller of FIG. 2.

FIG. 11 illustrates a detailed block diagram of an antenna directionacquisition controller of FIG. 2.

FIG. 12 illustrates a flow diagram of an antenna direction acquisitioncontroller of FIG. 2.

FIG. 13 illustrates a flow diagram of an example of a timer of FIG. 11.

FIG. 14 and FIG. 15 illustrate a flow diagram of an antenna scanprocessor of FIG. 11.

FIG. 16 illustrates a detailed block diagram of an antenna directiontracking controller of FIG. 2.

FIG. 17 illustrates a detailed block diagram of an antenna directionpower tracking error detector of FIG. 16.

FIG. 18 illustrates a detailed block diagram of an antenna directionmulti-channel power tracking error detector of FIG. 16.

FIG. 19 illustrates a detailed block diagram of an antenna direction SNRtracking error detector of FIG. 16.

FIG. 20 illustrates a detailed block diagram of an error integrator ofFIG. 16.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

In the present invention, a receiving performance of a receiver isimproved in a terrestrial channel in poor and kaleidoscope surroundingsby applying a smart antenna and an antenna control system to a digitalTV receiver. In other words, by optimizing the antenna system,reliability of the receiver is improved.

The present invention has a characteristic of coping with an environmentwherein a transmitting tower exists at different locations according toa broadcasting channel. In fact, this is a matter of a frequentoccurrence in other countries.

In general, because the digital TV receiver requires a limited stabletime, and a signal power detecting time takes up a long time in anantenna control process, the signal power detecting time is an importantfactor influencing an acquisition performance of the system.

A general early acquisition time of a smart antenna is objected to beless than one minute. To satisfy the limitation, a fast antennadirection acquisition performance is needed, which is an importantperformance factor of the smart antenna.

Together with this, the digital TV receiver detects a SNR(signal-to-noise ratio), multi-channel signal information, SER (segmenterror rate) for understanding quality of a receiving signal, and ittakes a long time to detect the SNR, multi-channel signal information,and SER.

Therefore, for fast acquisition performance, maximum signal power isdetected in a signal acquisition process and the smart antenna isconverged by selectively detecting signal power, multi-channel, SNR, andSER in a tracking process. Particularly, for detecting the maximumpower, the AGC (auto gain controller) is fixed at a predetermined valueand calculates signal power according to an antenna direction. In thetracking process, by continuously detecting channel information, thesmart antenna is controlled corresponding to a channel environmentchanging every hour.

Hereinafter, the digital TV receiving antenna control system and thecontrolling method of the same will be described in reference toappended drawings. FIG. 1 illustrates a conceptual diagram showing abasic algorithm of a digital TV receiving smart antenna control systemin accordance with the present invention.

As illustrated in FIG. 1, a basic concept of the antenna controlalgorism of the control system is that an optimal antenna direction isdetermined by acquiring the signal power at a predetermined degree (forexample, −180°, −90°, 0°, 90°, 180°) through 360° scanning of the smartantenna and by acquiring a maximum signal power location throughconverging the signal power to the antenna direction tracking loop in apredetermined degree unit.

FIG. 2 illustrates a block diagram of a digital TV receiving smartantenna control system including a smart antenna system 101, a VSBmodulator 102, and an antenna controller 103. First, the smart antennasystem 101 controls a beam width, a gain, a frequency characteristic bya mechanical or electrical antenna control signal of the antennacontroller 103 for an optimal antenna pattern for a signal reception.

As illustrated in FIG. 1, a basic concept of the antenna controlalgorithm of the control system is that an optimal antenna direction isdetermined by acquiring the signal power at a predetermined degree (forexample, −180°, −90°, 0°, 90°, 180°) through 360° scanning of the smartantenna and by acquiring a maximum signal power location throughconverging the signal power to the antenna direction tracking loop in apredetermined degree unit.

The AGC method illustrated in FIG. 3 is a method of removing gain of IFsignal of IF (intermediate frequency) AGC 402 through the charge pumpand filter 404 at the VSB receiving chip and removing gain of RF (Radiofrequency) signal of a tuner 401 by using a delayed AGC signal. In theAGC method illustrated in FIG. 4, the gains of the IF signal and the RFsignal are directly removed at the VSB receiving chip 503.

In other words, the AGC method for directly removing the gains of the IFsignal and the RF signal includes the steps of generating IF AGC controlsignal and RF AGC control signal by using a passband or basebandreceiving signal modulated with the RF AGC reference value at the VSBreceiving chip 503, and outputting each signal to IF AGC 502 and a tuner01.

The IF AGC 502 changes the gain of the IF signal into a desired state byincreasing or decreasing the gain of IF signal according to the IF AGCcontrol signal inputted from the IF AGC 502 and the tuner 501 changesthe gain of the RF signal by increasing or decreasing the gain of the RFsignal according to the RF AGC control signal.

Meanwhile, the antenna controller 103 controlling the smart antennasystem 101 mechanically or electronically through the channel dataincludes a channel information detector 103-1, an antenna directionacquisition controller 103-2, and an antenna direction trackingcontroller 103-3.

1) Channel Information Detector:

The channel information detector 103-1 detects channel data (forexample, AGC information, modulated I channel data, phase tracked Ichannel data, FEC error data, Field sync signals), determines thechannel condition, and outputs the detected channel information and thechannel conditions to the antenna direction acquisition controller 103-2and the antenna direction tracking controller 103-2.

For this, the channel information detector 103-1, as illustrated in FIG.5, includes a signal power detector 201 for outputting the signal powerinformation and the power condition, a multi-channel signal powerdetector 203 for outputting the multi-channel signal power informationand condition, a SNR detector 203 for outputting the SNR information andSNR condition, and a SER detector 204 for outputting the SER informationand the SER condition.

The signal power detector 201 includes a signal power informationcalculator 201-1 for detecting the signal power information from the IFgain and the RF gain, and a comparer 201-2 for comparing the signalpower information with a set signal power value and outputting thesignal power condition.

The multi-channel signal power detector 202 includes a signal powerinformation calculator 202-1 for detecting the multi-channel signalpower information from the equalizer input I channel data outputted fromthe demodulator 102 or the field sync signal, and a comparer forcomparing the multi-channel signal power information with the setmulti-channel signal power reference value so as to output themulti-channel signal power condition.

The SNR detector 203 includes a SNR information calculator (203-1) fordetecting the SNR information from the FEC input I channel data or thefield sync signal, and a comparer 203-2 for comparing the SNRinformation with the set SNR reference value so as to output the SNRcondition.

The SER detector 204 includes a SER information calculator 204-1 fordetecting SER information from a FEC error value outputted from thedemodulator 102, and a comparer 204-2 for comparing the SER informationand the set SER reference value so as to output the SER condition.

In this case, in the smart antenna control system, as illustrated inFIG. 4, the auto gain controller is provided to the VSB demodulator 102and gain control value (i.e., RG AGC control signal, IF AGC controlsignal) of the auto gain controller is set to a predetermined value inthe antenna direction acquisition process, so as to detect the signalpower by using the signal power detector illustrated in FIG. 6 or inFIG. 7.

In this instance, in the signal acquisition process of the antenna, aspecific value for fixing the auto gain controller in FIG. 4 is obtainedexperimentally through an experiment. In the present invention, as anembodiment, the auto gain control value with the band power of the inputRF signal about 60 dbm is used for fixing the gain controller.

Hereinafter, the signal power information calculator 201-1 included inthe channel information detector 103-1, the multi-channel informationcalculator 202-1, the SNR information calculator 203-1, and the SERinformation calculator 204-1 are described in detail.

1-1) Signal Power Information Calculator:

The signal power information calculator 201-1 is realized in two methodsas illustrated in FIG. 6 and FIG. 7. In a first method, the signal powerinformation calculator 201-1 includes a squaring operator 601 forreceiving a passband or baseband I signal from the VSB demodulator 102for obtaining a squared value, and an integrator 602 for accumulatingthe squared value into a predetermined window size for detecting thesignal power as illustrated in FIG. 6.

In other words, the squared operator 601 receives the passband orbaseband I signal from the VSB demodulator 102, obtains the squaredvalue and outputs the value to the integrator 602. The integrator 602accumulates the squared value into a predetermined size and divides theaccumulated value into a window size and outputs the value. The outputof the integrator 602 is the signal power information.

In a second method, the signal power calculator 201-1 detects the signalpower information by using an absolute value operator 701 and anintegrator 702 as illustrated in FIG. 7. In other words, the absolutevalue operator 701 receives the passaband and baseband I signal from theVSB demodulator 102, obtains the absolute value, and outputs the valueto the integrator 702. The integrator 702 accumulates the squared valueinto a predetermined size and divides the accumulated value into awindow size and outputs the value as the signal power information.

In this instance, in the antenna direction acquisition process, the gaincontrol value of the auto gain controller of FIG. 4 is fixed into aspecific value and detects the signal power by using the signal powerdetector 201. And then, when the antenna direction acquisition processis finished and the antenna direction tracking process is started, theauto gain controller forms a loop for controlling the auto gain controlamplifier and detects the signal power from the portion (integrator)storing the gain error in the loop.

1-2) Multi-Channel Signal Power Information Calculator:

The multi-channel signal power calculator 201-1 detects themulti-channel signal power information by using the field sync sectionas illustrated in FIG. 8. In other words, a degree of the ghost incontradiction to a main signal is calculated.

In this case, two detecting methods are proposed. First, relativemulti-channel information is detected on a basis of correlation value ofthe field sync signal when the multi-channel does not exist by usingonly the field sync signal of the main signal (nFSYNC). In other words,the multi-channel power information is detected by a train sequencegenerator 801 for detecting train sequence from the field sync signal ofthe main signal, a multiplier 802-1 for multiplying the output signaland input signal of the train sequence generator 801, an integerextractor 803-1 for obtaining only integers from the output of themultiplier 802-1, and a ghost power formalizer 804 for calculating andformalizing ghost power from the output of the integer extractor 803-1so as to detect the multi-channel power information.

Second, correlation value between the field sync signal of the mainsignal (nFSYNC) and the field sync signal of the multi-channel signals(gFSYNC) is calculated for finding the multi-channel information. Inother words, the multi-channel information is found by using a trainsequence generator 801 for generating train sequence of the main signaland of each multi-channel signal from the field sync signals of the mainsignal and the multi-channel signals (nFSYNC) (gFSYNC), number ofmultipliers (802-1, 802-2, . . . , 802−n) for multiplying the main andeach multi-channel train sequence outputted from the train sequencegenerator 801 with an input signal, n number of integer extractors(803-1, 803-2, . . . , 803−n) for extracting only the integer from eachoutput of the n number of multipliers (802-1, 802-2, . . . , 802−n), anda ghost power formalizer 804 for calculating and formalizing ghost powerfrom the output of the n number of integer extractors (803-1, 803-2, . .. , 803-2).

Therefore, in the method of using tab coefficient or tab energy of aconventional convergence of the channel equalizer is precondition andthe information detection is possible in only a limited environment.However, in the method of using the multi-channel information from amulti-channel signal power information calculator 202-1 proposed by thepresent invention, the by detecting the multi-channel information of thechannel equalizer, the limitation is relieved.

1-3) SNR Information Calculator:

FIG. 9 illustrates a block diagram showing SNR information calculator inFIG. 3. The following two methods are selectively used.

In a first method, that is a method of detecting error form field syncsignal of demodulated receiving signals, an MSE (mean square error)value is calculated from the received field sync signal and the trainsequence and the SNR is calculated by using the MSE value. In thismethod, data is renewed in each field through detecting the error fromthe field synchronized portion of the demodulated receiving signal. Inthis case, a subtractor 901 calculates difference between the receivedsync signal and the training sequence.

In a second method, the MSE value is calculated from demodulated andequalized I channel data (R_1) and decision constellation data (D_I),and the SNR is calculated from the MSE value. In other words, as amethod of detecting error of the equalized I channel data and decisionconstellation value, data is renewed in each window of the accumulator.In this case, the subtractor 901 calculates the difference between the Ichannel data (R_1) and the decision constellation data (D_I), andoutputs the calculation to the multiplier 902.

Then, the multiplier 902 multiplies the output of the subtractor 901 andoutputs the calculation to the accumulator 903 for an accumulation. Theaccumulator 903 temporarily stores the accumulated signal through alatch 904 and outputs to a modulo-operator 905. The modulo-operator 905counts the output of the latch 904 and resets the counted value to 0whenever the value is m. In this instance, the m is a window sizeinputted to the accumulator 903.

The SNR is expressed in a following formula (1).SNR=10·log(Ps/Pn)   (1)If, Ps is formalized as 1,

$\left. {Pn} \right|_{mse} = {\sum\limits_{k = 1}^{k = n}{\left( {{mse}/m} \right).}}$In this case, mse=(D_I−R_I)², R_I is received constellations, D_I isdecision constellations, m is a window size of the accumulator.

1-4) SER (Segment Error Rate)

The SER information calculator 204-1 receives the SER information fromthe VSB demodulator 102 and detects the Segment Error Rate. The SERinformation is reliable information and becomes a basis of finaldetermination for antenna convergence result.

2) Antenna Direction Acquisition Controller:

The antenna acquisition controller 103-2 receives channel conditioninformation (i.e., signal power condition, multi-channel powercondition, SNR condition and SER condition) and signal power informationfrom the channel information detector 103-1 and acquires the antennadirection.

FIG. 10 illustrates a diagram showing input/output signals of theantenna direction acquisition controller 103-2. In other words, asaforementioned, the input signal includes the channel conditioninformation, signal power information, and SYNCLOCK signals (Nsynclock)before EQ and before FEC of the channel equalizer.

While the antenna scans, the output signal outputs an EQ_freeze controlsignal for suspending update of the channel coefficient, an EQ_freezecontrol signal for maintaining the early coefficient value by resettingwhen the channel equalizer is diverged, a track_en control signal forstarting the antenna direction tracking process after the antennaacquisition process, an Ant_bw control signal for controlling a stepsize of the antenna direction by referring the channel conditioninformation (i.e., SNR, SER), a rescan control signal for initializingthe VSB demodulator 102 for reacquiring the antenna direction, an L_ensignal for notifying each delayed time satisfied at the timer, and anantenna direction acquisition signal.

FIG. 11 illustrates a detailed block diagram of an antenna directionacquisition controller in FIG. 2. As illustrated in FIG. 11, the antennadirection acquisition controller 103-2 includes an antenna scanprocessor 1102, a timer 1101, an antenna pattern counter register 1103,a signal power register 1104, a maximum signal power register 1105, andan antenna direction acquisition register 1106, and realized withhardware or software according to necessity. The structure has anadvantage that flexibility of the system is largely increased. Functionof the antenna direction acquisition controller 103-2 is schematicallydescribed as follows.

The antenna direction acquisition controller 103-2 detects the antennadirection of the maximum signal power by receiving the signal powerinformation from the channel information detector 103-1 and transmitsthe information to the antenna direction tracking controller 103-3. Thegain value of the auto gain controller of FIG. 4 is fixed as a specificvalue and the channel equalizer is stopped. After this, when theacquisition process is finished, the auto gain controller and thechannel equalizer are normally operated.

The antenna direction controller 103-2 receives each SYNCLOCK signal(Nsynclock) from the before EQ and the before FEC of the channelequalizer, determines an initialization of the channel equalizer,watches and prevents the divergence of the channel equalizer because thechannel equalizer may be diverged when the antenna is scanned. Forexample, it is viewed that the equalizer is diverged if the sync isfound at the before the channel equalizer and not found at the beforeFEC for a predetermined time.

Movement of the antenna direction acquisition controller 103-2structured as mentioned above is described as follows. FIG. 12illustrates a flow diagram showing a whole process of an antennadirection acquisition controller in FIG. 2.

1. The auto gain controller is fixed as a specific value (S1201-S1202).

2. The antenna direction is rotated to 360° and confirms whether thereceiving signal exists (S1203-S1208).

3. The antenna is rotated to 360° from the direction of the receivingsignal for acquiring the maximum signal power direction (S1209-S1214).

4. The antenna tracking process is started after acquiring the maximumsignal power direction (S1215-S1219).

5. Reception is watched by reading the channel condition information(S1219).

6. When the receiving condition is bad, the reacquisition process isprepared and the process of the step 1 is repeated (S1220-S1221).

Hereinafter, the antenna direction acquisition controller 103-2 isdescribed in more detail.

2-1) Registers:

The antenna pattern count register 1103 counts pattern number of thesmart antenna acquired during the antenna acquisition process, thesignal power register 1104 temporarily stores the signal powerinformation, the maximum signal power register 1105 stores the maximumsignal power value and the antenna direction, the antenna register 1106stores the antenna direction information at the maximum signal power andoutputs the antenna direction acquisition.

2-2) Timer:

The timer 101 calculates the delay time of each the process of the scanprocessor 1102. In this case, the flow diagram calculating the delaytime for each process is illustrated in FIG. 13. As illustrated in FIG.13, the delay time being a variable determined by environment andcondition is programmed at the timer 1101.

First, the variables being employed in FIG. 13 is defined as follows.Agc_set_cnt is a delay time for fixing the auto gain controller duringthe acquisition process, Ant_set_cnt is a delay time for setting theselected antenna pattern, Scan_set_cnt is a delay time for detecting thesignal power from the input signal, Rx_set_cnt is a delay time of thereceiver for converging, Con_set_cnt is a delay time for detecting thechannel condition information, rescan_set_cnt is a delay time forreacquiring process, and L_en is a signal notified by the timer fornotifying each delay time is satisfied when 1.

Hereinafter, the movement of the timer 110 will be described. First, thetimer initializes the variables in FIG. 13 (S1301), upon the delay time(L_en=Agc_set_cnt) for fixing the auto gain control value during theacquisition process, checks the delay time for setting the currentlyselected antenna pattern (S1303-S1304), and checks the delay time fordetecting the signal power inputted from the input signal (S1305-S1306),and then checks whether all the set antenna patterns are scanned(S1307). If the timer determines that all the set antenna directions arenot scanned, the timer scans a next antenna direction (S1308) andreturns to the step 1303 (S1303).

Meanwhile, if the timer determines that all the set antenna directionsare not scanned, the timer checks time for recovering the system(S1309-S1310) and checks the delay time (Con_set_cnt) consumed fordetecting the channel condition information. When the channel conditionabovementioned is all satisfied (S1313), the timer checks the delay time(rescan_set_cnt) consumed for reacquiring process (S1314-S1315).

2-3) Antenna Scan Processor:

The antenna scan processor 1102 outputs control signals needed for theacquisition process by receiving the signal power information and thechannel condition information (i.e., the signal power condition, multisignal power condition, SNR condition, and SER condition). In this case,the control signals of the scan processor 1102 in FIG. 14 to FIG. 7 areas follows.

First, as an internal control signal of the antenna scan processor 1102,(1) cnt_rst initializes the antenna pattern counter register 1103 whenthe cnt_rst is 1, (b) cnt is the antenna counter pattern value, (c)cnt_en allows counting of the antenna pattern counter register 1103 whenthe cnt_en is 1, (d) max_pw_rst initializes the maximum signal powerwhen the max_pw_en is 1, (e) max_pw_en allows renew of the maximumsignal power register value 1105 when max_pw_rst is 1, (f) offset_cnt_enallows renew of the antenna direction acquisition register value 1106,(g) max_cnt_en allows loading the maximum signal power antennaacquisition value from the maximum signal power register 1105 to theantenna direction acquisition register 1106 when the max_cnt_en is 1. Inthe mean time, as an external control signals of the antenna scanprocessor 1102, (h) track_en allows the antenna direction trackingprocess after finishing the antenna acquisition process when thetrack_en is 1, (i) ant_bw controls a step size of the antenna directionby looking at the channel condition information (i.e., SNR, SER), (j)agc_fz fixes the auto gain controller (AGC) in the process of theantenna direction process when the agc_fz is 1, (k) rescan initializesthe VSB demodulator 102 for reacquiring the antenna direction whenrescan is 1, (l) L_en is a signal for notifying that each delay time issatisfied at the timer 1101 when the L_en is 1.

Based on the control signal abovementioned, movement of the antenna scanprocessor 1102 illustrated in FIG. 14 and FIG. 15 is described asfollows.

First, the maximum signal power register 1105 and the antenna patterncounter register 1103 are initialized and the auto gain controller (AGC)is fixed as a specific value (S1401).

Second, the maximum signal power direction is acquired by rotating theantenna direction to 360° (S1501-S1504). In this case, the antennapattern counter register 1103 and the antenna direction acquisitionregister 1106 are renewed. If all the antenna patterns are checked, thestep 1406 is processed. (S1406). The auto gain controller is fixed at aspecific value.

Fourth, the maximum signal power antenna direction acquisition value isloaded from the maximum signal power register 1105 to the antennadirection acquisition register 1106 and the antenna counter register1103 is initialized (S1406).

Fifth, the antenna acquisition process is finished and the antennadirection tracking process is started (S1407-S1410). In this instance,the antenna pattern counter register 1103 is initialized. However, ifthe channel condition information (i.e., the signal power condition, SNRinformation condition) is not satisfied, the maximum signal powerregister 1105 is initialized and the VSB demodulator 102 is initializedfor reacquiring the antenna direction and rescanned (S1411).

3) Antenna Direction Tracking Controller:

The antenna tracking controller 103-3 receives the channel information(i.e., such as signal power, multi-channel signal power, SNR) from thechannel information detector 103-1, converges the antenna direction fromthe maximum signal power acquisition location to the optimal receivinglocation. When the smart antenna provides only a very simple antennapattern, for example, when having a plurality of antenna patterns, thetracking process is omitted.

However, when the antenna provides a tens of or hundreds of antennapatterns, effective receiving performance is improved, and the antennaenables to correspond to a channel environment changed every hour.

The antenna direction tracking controller 103-3, as illustrated in FIG.16, includes a signal power tracking error detector 1601, amulti-channel power tracking error detector 1602, a SNR tracking errordetector 1603, an error integrator 1604, and the antenna controlinterface 1605. Hereinafter, the antenna direction tracking controller103-3 is described in more detail.

3-1) Signal Power Tracking Error Detector:

FIG. 17 illustrates a detailed block diagram of a signal power trackingerror detector 1601. As illustrated in FIG. 17, the signal powertracking error detector 1601 includes a delayer 1701 for comparing thepresent antenna convergence direction for the signal power informationwith the previous convergence direction, a subtractor 1702, a signassignor 1703 for distinguishing the converged direction by adding apredetermined sign, and a multiplier 1704 and a delayer 1705 foroutputting the antenna convergence direction according to the comparisonresult.

The signal power tracking error detector 1601 structured asabovementioned regularly receives the signal power information from thechannel information detector 103-1 and outputs the antenna convergencedirection by the change of signal power information according to achange of the antenna direction.

For example, if the signal power is increased when the antennaconvergence direction is moved clockwise, the antenna convergencedirection is moved one more step clockwise. If the signal power isdecreased, the antenna convergence direction is moved counterclockwise.By repeating said process, the antenna convergence direction informationis outputted to the error integrator 1604.

3-2) Multi-Channel Signal Power Tracking Error Detector:

FIG. 18 illustrates a detailed block diagram of an antenna directionmulti-channel signal power tracking error detector 1602 of which thestructure is similar to the structure of FIG. 17 and will be omitted.The multi-channel signal power tracking error detector 1602 regularlyreceives SNR information from the channel information detector 103-1,watches the change of the multi-channel signal power informationaccording to the antenna direction change, and outputs the antennaconvergence direction.

For example, if the signal power is increased when the antennaconvergence direction is moved clockwise, the antenna convergencedirection is moved one more step clockwise. If the signal power isdecreased, the antenna convergence direction is moved counterclockwise.By repeating said process, the antenna convergence direction informationis outputted to the error integrator 1604.

Examples of many tracking error detectors are illustrated in FIG. 17 toFIG. 19, and various tracking error detectors to be proposed in thepresent invention may be applied. Antenna convergence information of aplurality of antenna tracking error detector are selectively assembledand employed in the antenna tracking process.

3-4) Error Integrator:

FIG. 20 illustrates a detailed block diagram showing an embodiment of anerror integrator 1604. The error integrator 1604 accumulates errors byreceiving and selectively assembling the antenna convergence informationfrom each tracking error detector 1601-1603. The accumulated error isconverged into an optimal antenna direction around the antenna directionof maximum signal power acquisition location.

Top value of the error accumulated at the error integrator 1604 isdivided into number of antenna patterns, and converged into the antennadirection. Detailed movement of the error integrator 1604 is as follows.In an antenna direction acquisition process (i.e., when track_en is 0),the signal power acquisition direction is loaded from the antennadirection acquisition controller 103-2 and in an antenna trackingprocess (i.e., track_en is 1), the antenna convergence directioninformation is accumulated. In this case, the antenna convergence rangeis limited according to the reception (i.e., SNR or SER condition). Forexample, if the reception is not satisfied after the antenna directionacquisition process, the antenna acquisition range is deviated from theadjacent antenna direction acquisition. If the reception is satisfied,the antenna acquisition convergence range is limited within the antennadirection acquisition location. Purpose of the limitation is forpreventing the antenna control system from being diverged.

Noap being number of the antenna patterns means a step size of theantenna direction. The antenna step size is controlled according to theantenna direction convergence. In general, in an early convergenceprocess, the step size is enlarged for a fast convergence and decreasedat an optimal convergence location for stabilizing the signal changeresulted form the tracking process.

3-5) Antenna Control Interface:

Antenna control interface 1605 means an interface between an antennacontrol system and a smart control system. The present inventionbasically supports US CEA/EIA 909 standard (a series data transmission)and other various interfaces may be supported. The antenna interfacechanges according to a kind of the smart antenna.

Meanwhile, the present invention can be applied to an antenna system ina filed of radio telecommunication such as VSB/OFDM.

As abovementioned, the digital TV receiving antenna control system hasadvantages as follows.

First, a process for controlling the smart antenna is divided into anacquisition process and a tracking process, and the tracking process isselectively omitted and applied to both a simple and complex smartantenna.

Second, in the acquisition process, the maximum signal power directionis detected by fixing AGC as a specific value. In other words, a methodof indirectly detecting a signal size from the AGC information of thetuner was conventionally used. However, in the present invention, amethod of directly calculating the signal power from an input signal isemployed and the method is highly reliable and the detecting speed isvery fast.

Third, the antenna controller of the present invention not only achievesoptimal antenna convergence but also corresponds to a channelenvironment changed every hour by selectively assembling various channelinformation and using the information in the tracking process.

Fourth, it is easy to make in one-chip and integration of the system isimproved because all controlling portions may be digital and flexibilityof the control system is secured because the antenna scan processincludes software.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A digital television (DTV) receiver having an antenna, comprising: anantenna system forming an optimal antenna pattern by adjusting a beamwidth, gain, and frequency characteristic of the antenna according to anantenna control signal; a demodulator demodulating a digital television(DTV) signal received from the antenna system and generating channeldata for an optimal antenna pattern; and an antenna controller receivingthe channel data from the demodulator and generating the antenna controlsignal using the channel data, wherein the antenna controller acquiresan antenna direction having a maximum signal power using a fixed autogain control (AGC) value and tracks a direction of the antenna using theacquired antenna direction.
 2. The digital television (DTV) receiver ofclaim 1, wherein the channel data comprise at least one of auto gaincontrol information, demodulated I channel data, phase-tracked I channeldata, forward error correction (FEC) error data, and a field syncsignal.
 3. The digital television (DTV) receiver of claim 1, wherein thedemodulator comprises an auto gain controller directly controlling again of a radio frequency (RF) signal and a gain of an intermediatefrequency (IF) signal.
 4. The digital television (DTV) receiver of claim1, wherein the antenna controller comprises: a channel informationdetector receiving the channel data from the demodulator and generatingchannel information and channel condition information; an antennadirection acquisition controller receiving the channel information andthe channel condition information and acquiring the antenna directionhaving the maximum signal power using the channel information and thechannel condition information; and an antenna direction trackingcontroller generating the antenna control signal using the acquiredantenna direction and tracking the direction of the antenna using theantenna control signal.
 5. The digital television (DTV) receiver ofclaim 1, wherein the channel information detector comprises: a signalpower information calculator calculating a signal power by using one ofa passband and baseband I-signal received from the demodulator; amulti-channel signal power information calculator calculatingmulti-channel signal power information by using one of a field syncsignal and equalized I-channel data in the channel data received fromthe demodulator; a SNR information calculator calculatingsignal-to-noise (SNR) information from one of forward error correction(FEC) input I-channel data and the field sync signal in the channel datareceived from the demodulator; and a SER information calculatorcalculating segment error rate (SER) information from FEC error data inthe channel data received from the demodulator.
 6. The digitaltelevision (DTV) receiver of claim 5, wherein the signal powerinformation calculator receives and squares the one of a passband andbaseband I-signal, accumulates the squared values according to apredetermined window size, and outputs signal power informationaccording to accumulated values.
 7. The digital television (DTV)receiver of claim 5, wherein the signal power information calculatorreceives the one of a passband and baseband I-signal, determinesabsolute values of the one of a passband and baseband I-signal,accumulates the absolute values according to a predetermined windowsize, and outputs signal power information according to accumulatedvalues.
 8. A digital television (DTV) receiver having an antenna,comprising: an antenna system forming an optimal antenna pattern byadjusting a beam width, gain, and frequency characteristic of theantenna according to an antenna control signal; a demodulatordemodulating a digital television (DTV) signal received from the antennasystem and generating channel data for an optimal antenna pattern; andan antenna controller receiving the channel data from the demodulatorand generating the antenna control signal using the channel data,wherein the channel data comprise at least one of auto gain control(AGC) information, demodulated I-channel data, phase-tracked I-channeldata, forward error correction (FEC) error data, and a field syncsignal, and wherein the antennal is traced to a direction having amaximum signal power obtained by using a fixed auto gain control (AGC)value.
 9. The digital television (DTV) receiver of claim 8, wherein thedemodulator comprises an auto gain controller directly controlling again of a radio frequency (RF) signal and a gain of an intermediatefrequency (IF) signal.
 10. The digital television (DTV) receiver ofclaim 8, wherein the antenna controller comprises: a channel informationdetector receiving the channel data from the demodulator and generatingchannel information and channel condition information; an antennadirection acquisition controller receiving the channel information andthe channel condition information and acquiring an antenna directionhaving the maximum signal power using the channel information and thechannel condition information; and an antenna direction trackingcontroller generating the antenna control signal using the acquiredantenna direction and tracking the direction of the antenna using theantenna control signal.
 11. An antenna system for use in a digitaltelevision (DTV) receiver, the antenna system comprising: an antennareceiving a digital television (DTV) signal; and an antenna phase andgain controller forming an optimal antenna pattern by adjusting a beamwidth, gain, and phase of the antenna according to an antenna controlsignal, wherein the antennal control signal is generated by acquiring anantenna direction having a maximum signal power using a fixed auto gaincontrol (AGC) value and by tracking a direction of the antenna using theacquired antenna direction.
 12. The antenna system of claim 11, whereinthe antenna control signal is generated using channel data of the DTVsignal and the channel data comprise at least one of auto gain control(AGC) information, demodulated I-channel data, phase-tracked I-channeldata, forward error correction (FEC) error data, and a field syncsignal.
 13. An antenna control system for controlling an antenna,comprising: a demodulator demodulating the signals received through theantenna and generating channel data from the received signals; and anantenna controller receiving the channel data from the demodulator,generating an antenna control signal using the channel data andcontrolling a direction of the antenna by using the antenna controlsignal, wherein the channel data include at least one of auto gaincontrol (AGC) information, demodulated I-channel data, phase-trackedI-channel data, forward error correction (FEC) error data, and a fieldsync signal, and wherein the antennal is traced to a direction having amaximum signal rower obtained by using a fixed auto gain control (AGC)value.
 14. The antenna control system of claim 13, wherein thedemodulator comprises an auto gain controller directly controlling again of a radio frequency (RF) signal and a gain of an intermediatefrequency (IF) signal.
 15. The antenna control system of claim 13,wherein the antenna controller comprises: a channel information detectorreceiving the channel data from the demodulator and generating channelinformation and channel condition information; an antenna directionacquisition controller receiving the channel information and the channelcondition information and acquiring a direction of the antenna having amaximum signal power using the channel information and the channelcondition information; and an antenna direction tracking controllergenerating the antenna control signal using the acquired antennadirection and tracking the direction of the antenna using the antennacontrol signal.
 16. The antenna control system of claim 15, wherein thechannel information detector comprises: a signal power informationcalculator calculating a signal power by using one of a passband andbaseband I-signal received from the demodulator; a multi-channel signalpower information calculator calculating multi-channel signal powerinformation by using one of a field sync signal and equalized I channeldata in the channel data received from the demodulator; a SNRinformation calculator calculating signal-to-noise (SNR) informationfrom one of forward error correction (FEC) input I-channel data and thefield sync signal in the channel data received from the demodulator; anda SER information calculator calculating segment error rate (SER)information from the FEC error data in the channel data received fromthe demodulator.
 17. The antenna control system of claim 16, wherein thesignal power information calculator receives and squares the one of apassband and baseband I-signal, accumulates the squared values accordingto a predetermined window size, and outputs signal power informationaccording to accumulated values.
 18. The antenna control system of claim16, wherein the signal power information calculator receives the one ofa passband and baseband I-signal, determines absolute values of the oneof a passband and baseband I-signal, accumulates the absolute valuesaccording to a predetermined window size, and outputs signal powerinformation according to accumulated values.
 19. An antenna controlmethod comprising: receiving a digital television (DTV) signal throughan antenna; demodulating the received digital television (DTV) signaland generating channel data; generating an antenna control signal usingthe channel data; and continuously controlling an antenna directionaccording to the antenna control signal, wherein the antenna controlsignal is generated by acquiring the antenna direction having a maximumsignal power using the channel data according to a fixed auto gaincontrol (AGC) value.
 20. The antenna control method of claim 19, whereinthe channel data comprise at least one of auto gain control (AGC)information, demodulated I-channel data, phase-tracked I-channel data,forward error correction (FEC) error data, and a field sync signal.